1. Field of the Invention
This invention relates to a padlock, more particularly to a padlock having a lock device that is suitable for use with lock bases of different sizes.
2. Description of the Related Art
FIG. 1 illustrates a conventional padlock which includes a lock base 10, a lock device 11, two ball members 12, and a U-shaped shackle 13. The lock base 10 is formed with two shackle insert holes 16 for receiving longer and shorter leg portions of the shackle 13, a lock receiving space 14 between the shackle insert holes 16 for receiving the lock device 11, and two ball chambers 15 on opposite sides of an upper section of the lock receiving space 14 to communicate the lock receiving space 14 with the shackle insert holes 16, respectively. The lock device 11 is formed with an engaging rim 111 for retaining the lock base 10 in the lock receiving space 14. The lock device 11 has an upper end formed with a plunger 112 which has two opposite latch portions 113 for actuating the ball members 12, respectively. When the padlock is in a locking state, the ball members 12 are pushed by the latch portions 113 of the plunger 112 to extend into the shackle insert holes 16 for engaging ball retaining grooves 131 formed in the longer and shorter leg portions of the shackle 13 in order to prevent upward movement of the shackle 13 and removal of the shorter leg portion from the corresponding shackle insert hole 16. When the lock device 11 is operated using the correct key (not shown) to rotate a lock core (not shown) in the lock device 11, the plunger 112 is rotated to permit retraction of the ball members 12 into the ball chamber 15 for disengaging the shackle 13, thereby permitting upward movement of the shackle 13 and removal of the shorter leg portion from the corresponding shackle insert hole 16 for placing the padlock in an unlocked state.
In the conventional padlock, when it is required to produce a lock base with a different size, such as a different width, the original lock device cannot be used, and a new lock device with a different size is produced so as to fit the lock base. Since a lock device generally has a relatively complicated and delicate structure in order to provide a good antitheft effect, the design and manufacture of a new lock device result in great expense.
In applicant's co-pending U.S. patent application Ser. No. 08/992,444, filed on Dec. 17, 1997 and entitled "PADLOCK WITH REPLACEABLE KEY-OPERATED LOCK CORE," there is disclosed a padlock which includes a lock base, a lock unit, a shackle, and catch means. The lock base is formed with first and second shackle insert holes for receiving longer and shorter leg portions of the shackle, and a lock receiving space between and parallel to the first and second shackle insert holes for receiving the lock unit. The lock receiving space has an upper section formed as a catch chamber which extends between the shackle insert holes for receiving the catch means. The lock unit includes an axially rotatable key-operated lock core having a plunger disposed in the catch chamber. The second shackle insert hole has an innermost end provided with a spring-loaded retaining means which extends radially into the lock receiving space to engage a peripheral portion of the lock unit so as to retain releasably the lock unit in the lock receiving space. The catch means includes first and second catch units, each of which is provided with a ball member, and a spring for pulling together the catch units such that the ball members engage the plunger. When the plunger is in the locking position, the plunger forces apart the first and second catch units so as to extend the ball members into the shackle insert holes such that the ball members engage the longer and shorter leg portions of the shackle, respectively. When the lock unit is operated using the correct key to cause axial rotation of the plunger, the plunger ceases to force apart the first and second catch units, thereby retracting the first and second catch units into the catch chamber by virtue of the spring in order to permit upward movement of the longer leg portion and removal of the shorter leg portion from the second shackle insert hole. After the shorter leg portion has been removed from the second shackle insert hole of the lock base, the longer leg portion can be rotated to expose the second shackle insert hole. In this situation, a tool can be inserted into the second shackle insert hole so as to access and actuate the retaining means for disengaging the latter from the locking unit, thereby permitting removal of the lock unit from the lock receiving space for replacement purposes.